Build Quality

Overall build quality is very solid. There is no rattle when shaking the mouse. When applying lateral pressure, no creaking or flexing of the shell can be observed. Activating the side buttons by squeezing the sides is impossible. Lastly, no accidental clicks occur when slamming down the mouse.

Buttons

Main buttons on the Castor Pro are very good. While pre-travel is very low on the right button, it is moderately high on the left one, and post-travel is moderate on either. Still, the switches themselves provide a clearly defined and snappy response. The buttons can still be actuated quite far back on the mouse, though the shell imparts a high degree of rigidity in that case. Button stiffness is medium. A pair of Kailh GM 8.0 (80 M) switches is used.


Side buttons are good. While the click feel is rather pleasing, the forward button in particular has significant pre-travel, which is less pronounced on the back button, but that one in turn suffers from significant post-travel. The back button also suffers from an uneven actuation point, which further adds to the mushiness. Button placement is good as actuation is possible very easily by rolling one's thumb across. A pair of TTC switches (red plunger) is used here.

At the top of the mouse is a single button for cycling through the set CPI steps, which works just fine. Another TTC switch (white plunger) is used for this one.

Scroll Wheel

The scroll wheel is good. Scrolling in either direction is quite noisy, but tactility is good, providing clearly discernible steps and no accidental scrolling. Most notably, compared to other wheel designs, this one sits quite a bit lower, so that it barely sticks out. The encoder comes from ALPS (black core) and has a height of 11 mm. The middle (scroll wheel) click requires low force for actuation. Yet another TTC switch (white plunger) is used for this one.

Coating

The Castor Pro has a smooth matte surface all over except for the left side, which is textured hardened rubber. The former doesn't attract fingerprints, dirt, or the likes too much. It is easy to clean, and there are barely any signs of wear left after doing so. All in all, very good materials.

Button Sound Test

Disassembly

Disassembling the Castor Pro is very easy. Just remove the rear skate and the screws beneath it, and pop the top and bottom shell apart. While the internal design isn't as inefficient as on the Naos Pro, saving weight clearly was no concern on this one either. The top and side buttons sit on their own PCB screwed into the top shell and are connected through a 4-pin connector. An auxiliary PCB for illumination purposes can be found next to the scroll wheel. All PCBs are incredibly thick, and the main PCB in particular has a decent amount of unused space. Production date for the main PCB is the 49th week of 2020. Three screws are used to secure the main PCB to the bottom shell. The MCU is an STM32L072RBT6, whose datasheet can be found here.


As for the soldering and general quality of the PCB, I'm unable to find any noteworthy flaws.